1. Field of the Invention
The present invention relates to a new and improved apparatus for the metered dosing of flowable or fluent masses, especially liquidous and pasty material masses.
Generally speaking, the metering apparatus of the present development comprises a rotatable drum member or drum rotatable about a substantially horizontal lengthwise axis. This drum member contains a substantially cylindrical outer shell or jacket provided with a plurality of openings or perforations, especially circular or round openings or perforations. Rotatably arranged within this drum member is a roller member having a lengthwise axis. This lengthwise axis of the roller member and the lengthwise axis of the drum member are arranged substantially parallel and eccentric to one another, and optionally these lengthwise axes can be moved relative to one another. Beneath the drum member there is arranged a transport device or member, for example, an endless transport belt or band, for receiving the metered mass portions, especially mass droplets or globules of the processed material. If desired, these mass droplets or globules can solidify upon the transport device or member.
2. Discussion of the Background and Material Information
The metered dosing or apportionment of material masses, in particular pasty including liquidous masses of materials to be processed usually constitutes one of the last process steps during the manufacture of chemicals, foodstuffs or also pharmaceutical products. Depending upon the encountered requirements, there are prescribed for the manufacturing operation a predetermined shape of the delivered portions of the metered material mass undergoing processing or a predetermined quantity of the delivered dosed portions, or else both such factors are prescribed. The metered or dosed quantities of processed material mass delivered by a corresponding metering apparatus are usually supplied to transport devices, especially endless belts or bands, where the deposited material mass is solidified either by heating or cooling thereof.
During the delivery of the material mass from a rotating drum member, it is desired, both from the standpoint of having a constant volume of the metered material mass portions and a constant dimensional shape or form, to avoid any pre-flow or post-flow of the processed material. Furthermore, there should be possible the attainment of reproducible metered portions of the delivered material mass undergoing processing irrespective of the region of the drum member through which passes the material mass.
In German Patent Publication No. 1,941,460, published Mar. 11, 1971, there is disclosed an apparatus for the droplet-shape delivery of pressable material masses from a vat or container. The metered dosing of the material masses is accomplished by means of a diaphragm. Owing to the reproducible motion of the diaphragm and the thus required construction of the apparatus, there occurs an accumulation of the material or substance to be eliminated between the vat and the diaphragm. Hence, after the expiration of a relatively short amount of service time of the apparatus, it is necessary to perform extensive cleaning of such apparatus in order to ensure that there can be realized an exact metering of the processed material mass.
According to another prior art apparatus as disclosed in German Patent Publication No. 3,819,558, published Dec. 14, 1989, nozzles are provided at the lower region of a heated vat or container. The material mass emerges through such nozzles and is subdivided into individual material droplets by means of a shaped vane. These material droplets then descend onto a cooling band located therebelow. With this prior art apparatus it is not possible to reproduce upon the cooling band either the shape or the quantity of the deposited metered portions of the processed material mass.
In the European Published Patent Application No. 244, 849, published Nov. 11, 1987, constituting a starting point in the consideration of the metering apparatus of the present invention, there is taught a granulation apparatus containing a perforated hollow drum member. The inner surface of this perforated hollow drum member is provided with teeth. The teeth of a drum or roller arranged within such perforated hollow drum member engage with the teeth of this perforated hollow drum member. The material mass to be granulated is introduced into the perforated hollow drum member and, as a result of the rotational movement of such perforated hollow drum member, is introduced into the tooth gaps or spaces of the meshing teeth and from this location is pressed out by the drum or roller entrained by the perforated hollow drum member. If there are used involute teeth, then by adjusting the mutual spacing between the lengthwise axes of these drums it is intended to influence the volume of the spaces enclosed between tooth ledges. An endless belt arranged beneath the granulation apparatus receives the delivered material mass dripping out of the granulation apparatus. Additionally, it is contemplated to achieve a change in the volume of the pressed out material mass droplets by exchanging the drum and tooth ledges situated internally of the perforated hollow drum member.
What is disadvantageous with this type of prior art equipment, is that a volume change of the droplets only is possible within a very small region which is governed by the closed space of the teeth of the perforated hollow drum member and the drum or roller. As a result of this drawback, the quantity of the dripping-out material mass is markedly dependent upon the material mass viscosity, since there occurs a return flow of the material mass through the spaces or gaps of the teeth when the space is not yet closed. Moreover, there practically cannot be avoided pre-dripping and post-dripping of the material mass, since there only can occur to a limited extent a sucking-back of the material mass into the hollow cylinder of the hollow drum member, and specifically, at that region where the spaces between the teeth are closed, and the volume increases due to the rotational movement of the hollow drum member and the internal drum or roller. Additionally, by virtue of the positive driving of either the outer hollow drum member or the inner drum or roller by the other coacting cylindrical member, abrasion occurs at the teeth. As a result thereof, there arises with time, on the one hand, wear and thus a volume change, and, on the other hand, the worn or abraded particles are mixed with the material mass to be pressed out, resulting in an undesired contamination of the obtained product. Of course, these same observations hold true even if, as proposed in such patent document, the teeth are formed of plastic material.